In integrated circuit (IC) manufacturing, fabrication of seal rings (also known as protective rings) is an important part of the semiconductor process. With the development of semiconductor technology, IC is made in the form of a chip. Specifically, semiconductor structures or semiconductor devices constituting an IC are formed on the surface of a semiconductor substrate or wafer. The semiconductor substrate or wafer is then sawed to form a plurality of separated chips. However, when the semiconductor substrate or wafer is sawed, mechanical stress is applied to the semiconductor substrate or wafer, and tends to generate cracks in the chips formed by sawing.
Furthermore, multiple semiconductor devices are generally formed on a semiconductor substrate. Thus, during a process of fabricating the semiconductor devices, stacked insulating films, e.g., inter-metal dielectric (IMD), and inter-layer dielectric (ILD), are formed by deposition. The stacked insulating films can be exposed at sidewall surfaces of a chip due to the chip sawing process. The stacked insulating films and their surface exposed at the sidewall surfaces of the chip can form a path for moisture penetration, and can result in malfunction of the semiconductor devices.
In order to prevent a semiconductor chip from being damaged by chip sawing process and to avoid degradation induced by moisture, a seal ring structure is formed between a device region and a saw Lane of each chip. Conventionally, the seal ring structure is formed at the same time during a process for forming a wiring layer and a contact portion. The formed seal ring structure has a multi-layer structure that is formed by alternately-stacked metal layers and insulating layers. Via holes are formed in each insulating layer for connecting adjacent metal layers.
However, existing seal ring structure still has poor performance in protecting device regions of a chip, and thus often affects properties of the chip formed by sawing. The disclosed methods and structures are directed to solve one or more problems set forth above and other problems.